LAUSR

Background Little is known about non-adherence to HBV therapy. This study aimed to investigate the relationship between self-reported missed days of antiviral therapy and HBV virological breakthrough and factors associated with virological breakthrough. Methods A cross-sectional survey of 211 HBV patients receiving oral antiviral therapies was undertaken at three tertiary hospitals in Sydney, Australia. Associations between 0 to >6 missed days in the last 30 days and virological breakthrough (defined as >10-fold rise in serum HBV DNA above nadir or after achieving virological response in the last 12 months) were examined. Logistic regression analyses determined the number of missed days most strongly associated with virological breakthrough and the associated factors. We report odds ratios (ORs) and relative risks (RRs). Results Of the 204, 32 participants (15.6%) had quantifiable HBV DNA levels (>20 IU/ml); 15 (46.8%) of them experienced virological breakthrough. Participants reported never missing medication (n=130, 63.7%) or missing 1 day (n=23, 11.3%), >1 day (n=23, 11.3%), 2–6 days (n=15, 7.3%) and >6 days (n=13, 6.4%). The most discriminating definition of non-adherence was missing >1 day of medication (RR=8.3; OR=10.2, 95% CI 3.1, 33.8, receiver operating characteristic curve 0.76). Factors independently associated with virological breakthrough included non-adherence (OR=9.0, 95% CI 2.5, 31.9) diagnosed with HBV ≤14 years (OR=5.3, 95% CI 1.0, 26.2) and age ≤47 years (OR=5.4, 95% CI 1.1, 26.9). Conclusions Results provide an evidence-based definition of non-adherence to inform clinical practice and provide a basis for key patient education messages. Closer monitoring of groups at risk of viral breakthrough is required.